Rehmannia has been used extensively in traditional Chinese medicine (TCM). Although thorough clinical trials are lacking, rehmannia has been used to treat rheumatoid arthritis, asthma, urticaria (hives), and chronic nephritis (kidney inflammation) in Chinese studies. Rehmannia may also be used to prevent the suppressive effects of corticosteroid (steroid) drugs.

Rehmannia looks promising in treating aplastic anemia, mitigating side-effects of chemotherapeutic agents and HIV medications, curing obdurate eczema (dry skin), relieving pain from lung or bone cancer or disc protrusion, and helping ameliorate lupus nephritis (kidney inflammation) and type 2 diabetes with hyperlipidemia (high cholesterol). However, presently, there are no high-quality, large randomized, controlled trials supporting the efficacy of rehmannia for any of these indications.

Rehmannia is in the Pharmacopoeia of the People's Republic of China. However, it is not on the United Kingdom's General Sale List, and is not covered by a Commission E monograph in Germany. The U.S. Food and Drug Administration (FDA) has not granted generalized recognized as safe (GRAS) status to rehmannia; it is available in the United States as a dietary supplement under the Dietary Supplement Health and Education Act of 1994.

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

GRADE *

Rehmannia is frequently recommended to mitigate duration and severity of aplastic anemia. Although preliminary results appear promising, additional study is needed to draw a firm recommendation.

C

Rehmannia glutinosa has been used in the treatment of Sheehan's syndrome. However, the magnitude of therapeutic effects of rehmannia on Sheehan's syndrome remains unclear. More research is necessary in this area.

C

* Key to grades

A: Strong scientific evidence for this useB: Good scientific evidence for this useC: Unclear scientific evidence for this useD: Fair scientific evidence for this use (it may not work)F: Strong scientific evidence against this use (it likley does not work)

Tradition / Theory
The below uses are based on tradition, scientific theories, or limited research. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. There may be other proposed uses that are not listed below.

There is no proven safe or effective dose for rehmannia. Herbal decoctions used in clinical trials have contained 12-30 grams of rehmannia. For Sheehan's syndrome, 90 grams of cleaned and finely chopped Rehmannia glutinosa root added to 900 milliliters of water and boiled down to 200 milliliters has been used in three day courses with an intermission of three, six, and 14 days. After a one-month cessation, the second round of treatment commenced. Another dosing regimen used was 45-50 grams of Rehmannia glutinosa daily in five-day courses with an intermission of five days each time for 2-5 months.

Children (younger than 18 years):

There is no proven safe or effective dose for rehmannia in children.

Safety
The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

Allergies

Avoid in individuals with a known allergy or hypersensitivity to rehmannia.

Side Effects and Warnings

Rehmannia has been generally well tolerated in available research studies. It has been well tolerated for 20 days to 1.2 years in human trials. Rehmannia may cause palpitations, edema (swelling), gastrointestinal upset, infertility, dizziness, and lack of energy. Use cautiously in patients with diabetes, as rehmannia may lower blood sugar or additively effect hypoglycemic (low blood sugar) agents. Avoid in patients with diarrhea and lack of appetite due to possible irritation of gastrointestinal tract by rehmannia.

The concomitant use of aminoglycosides and rehmannia may decrease toxicity associated with aminoglycoside therapy.

Man-Shen-Ling is a combination product that contains rehmannia, which may increase the risk of bleeding when taken with drugs that increase the risk of bleeding. Some examples include aspirin, anticoagulants ("blood thinners") such as warfarin (Coumadin®) or heparin, anti-platelet drugs such as clopidogrel (Plavix®), and non-steroidal anti-inflammatory drugs (NSAIDS) such as ibuprofen (Motrin®, Advil®) or naproxen (Naprosyn®, Aleve®).

Rehmannia may interact with antihistamines.

Although not well studied in humans, Liu wei di huang t'ang (decoction of rehmannia with six components) may lower blood pressure. Caution is advised in patients with high blood pressure or taking any antihypertensive (blood pressure lowering) agents.

Rehmannia and corticosteroids (steroids) may result in a synergistic effect and possibility of reduced side effects.

Rehmannia may interact additively with drugs that alter blood sugar because it can cause hypoglycemia (low blood sugar). Caution is advised in patients with diabetes or hypoglycemia and in those taking drugs that affect blood sugar. Serum glucose levels may need to be monitored by a healthcare provider, and medication adjustments may be necessary.

The concomitant use of cholesterol-lowering drugs with rehmannia may result in additive effects.

Rehmannia may have an additive effect with thyroid drugs. In a study on Sheehan's syndrome, Rehmannia glutinsoa may have improved clinical symptoms and stimulated the hypothalamic-pituitary system.

Interactions with Herbs and Dietary Supplements

Rehmannia may increase the risk of bleeding when taken with herbs and supplements that are believed to increase the risk of bleeding. Multiple cases of bleeding have been reported with the use of Ginkgo biloba, and fewer cases with garlic and saw palmetto. Numerous other agents may theoretically increase the risk of bleeding, although this has not been proven in most cases.

Combination use of rehmannia with herbs/supplements that lower blood pressure may result in additive effects.

Rehmannia and corticosteroids (steroids) may result in a synergistic effect and there is a possibility of reduced side effects. Caution is advised in patients taking herbs with steroid-like effects.

Rehmannia may have an additive effect with diuretics, such as astragalus.

Rehmannia may interact additively with herbs that affect blood sugar because it may cause hypoglycemia (low blood sugar). Seishin-kanro-to, composed of rehmannia radix, may lower blood sugar levels. Caution is advised in patients with diabetes or hypoglycemia, and in those taking herbs or supplements that affect blood sugar. Serum glucose levels may need to be monitored by a qualified healthcare provider, and medication adjustments may be necessary.

The concomitant use of cholesterol-lowering herbs, such as red yeast rice, with rehmannia may result in additive effects.

The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.